Abstract [en]

In a Galactic core-collapse supernova (SN), axionlike particles (ALPs) could be emitted via the Primakoff process and eventually convert into gamma rays in the magnetic field of the Milky Way. From a data-driven sensitivity estimate, we find that, for a SN exploding in our Galaxy, the Fermi Large Area Telescope (LAT) would be able to explore the photon-ALP coupling down to g(a gamma) similar or equal to 2 x 10(-13) GeV-1 for an ALP mass m(a) less than or similar to 10(-9) eV. These values are out of reach of next generation laboratory experiments. In this event, the Fermi LAT would probe large regions of the ALP parameter space invoked to explain the anomalous transparency of the Universe to gamma rays, stellar cooling anomalies, and cold dark matter. If no gamma-ray emission were to be detected, Fermi-LAT observations would improve current bounds derived from SN 1987A by more than 1 order of magnitude.